Patients with diabetes suffer from premature atherosclerosis of large vessels and this constitutes a major reason for increased morbidity and mortality in this population. Diabetics also suffer from a microvascular lesion with equally deleterious results. Recent experimental data suggest that this lesion may be at least partially related to poor metabolic control. Attempts at achieving prolonged normalization of the metabolic derangements of diabetes and delaying the vascular complications of the disease have met with little success. Physical training in normal man decreases plasma triglycerides and increases plasma HDL-cholesterol. Training further increases apparent peripheral sensitivity to insulin and has a wide variety of other possibly beneficial metabolic and hematologic effects. We intend to study the effects of a program of regular physical training in an outpatient population with uncomplicated non-insulin-dependent diabetics. Baseline fitness will be established and patients will train 3-4 times a week. Metabolic parameters will be followed at 6 weeks and 3 and 6 months. Improvements in fitness will be judged by changes in maximal oxygen uptake. Training will be at a level estimated to increase VO Max, 20 percent over basal in 6 weeks. This will be correlated with changes in lipoprotein profiles including HDL-cholesterol. Changes in insulin sensitivity and glucose tolerance will be assessed by serial I.V. and P.O. glucose tolerance testing with Hbg A1C levels. Pertinent hematologic data and psychological alterations will be followed sequentially as well. Effects of training on abnormal hormonal regulation found in diabetics will be assessed by serially determining suppressibility of hGH and glucagon to a glucose challenge and by assessing basal and exercise-related enhancement of catecholamines and growth hormone secretion. This work will establish the effects of physical training on a variety of vascular rish factors associated with the diabetic state and may establish exercise therapy as a therapeutic modality for adult diabetics.